Question 1

How could IR spectroscopy be used to distinguish between the following pair of compounds?
CH3COCH-CHCH2CH3 and CH3COCH2CH2CH-CH2

Accepted Answer

C-O absorption in co...

Question 2

Which region of the electromagnetic spectrum, radio or visible, is characterized by waves of shorter wavelength?

Accepted Answer

The answer of Which region of the electromagnetic spectrum, radio...

Question 3

Which compound has a single, weak IR absorption at 3300 cm-1?

Accepted Answer

A)   (CH3CH2) 2NH
B)   CH3CH2CH2OH
C)   CH3CH2CN
D)   (CH3CH2) 2O
E)   CH3CH=CHCH3F) A) and C)
G) B) and E)

Question 4

Which has the higher speed in a vacuum, ultraviolet or infrared light?

Accepted Answer

They have ...

Question 5

The presence of which element is indicated by a peak at m/z 127 and a characteristic 127-unit gap in the mass spectrum?

Accepted Answer

A)   Br
B)   Cl
C)   I
D)   N
E)   SF) B) and E)
G) None of the above

Question 6

Which compound would be expected to show intense IR absorption at 2820, 2710 and 1705 cm-1?

Accepted Answer

A)   CH3COCH2CH3
B)   PhCOCH3
C)   PhCHO
D)   CH2=CHCOCH3E) C) and D)
F) All of the above

Question 7

Which compound lacks a strong, characteristic IR absorption near 1700 cm-1?

Accepted Answer

A)   CH3CH2CO2H
B)   CH3CH2CHO
C)   (CH3CH2) 2C=O
D)   (CH3CH2) 2O
E)   H3CH2CO2CH3F) C) and E)
G) B) and C)

Question 8

Ethyne (HC꓿CH)  does not show IR absorption in the region 2000-2500 cm-1 because:

Accepted Answer

A)   C­H stretches occur at lower energies.
B)   C꓿C stretches occur at about 1640 cm-1.
C)   there is no change in the dipole moment when the C꓿C bond in ethyne stretches.
D)   there is a change in the dipole moment when the C꓿C bond in ethyne stretches.E) None of the above
F) All of the above

Question 9

An infrared wavelength of 5.81μm is equivalent to a wavenumber of ________ cm-1.

Accepted Answer

Question 10

Which region of the electromagnetic spectrum, IR or X-ray, is characterized by waves of lower frequency?

Accepted Answer

The answer of Which region of the electromagnetic spectrum, IR...

Question 11

Which of the following has a C→H stretch that occurs at the highest stretching frequency?

Accepted Answer

A)   hexane
B)   hex-1-ene
C)   (
E)  -hex-2-ene
D)   hex-1-yne
E)   hex-2-yneF) None of the above
G) C) and E)

Question 12

What IR absorption is characteristic of the carbon-carbon triple bond stretch in alkynes?

Accepted Answer

A)   3500 cm-1
B)   3300 cm-1
C)   2950 cm-1
D)   2250 cm-1
E)   1710 cm-1F) B) and D)
G) C) and D)

Question 13

Which of the following fragment peaks would not be present in the mass spectrum of n-hexane?

Accepted Answer

A)   87
B)   71
C)   57
D)   43
E)   29F) A) and B)
G) C) and D)

Question 14

Which compound would be expected to show intense IR absorption at 1746 cm-1?

Accepted Answer

A)   CH3CH2OCH2CH3
B)   CH3CH2CN
C)   CH3CO2CH2CH3
D)   CH3CH2SCH3E) A) and B)
F) A) and C)

Question 15

The region of the IR spectrum which contains the most complex vibrations (600-1400 cm-1) is called the ________ region of the spectrum.

Accepted Answer

Question 16

What IR absorption is characteristic of the C=O stretch in aldehydes?

Accepted Answer

A)   3500 cm-1
B)   3300 cm-1
C)   2950 cm-1
D)   2250 cm-1
E)   1710 cm-1F) All of the above
G) None of the above

Question 17

Absorption of what type of electromagnetic radiation results in electronic transitions?

Accepted Answer

A)   X-rays
B)   radio waves
C)   microwaves
D)   ultraviolet light
E)   infrared lightF) A) and D)
G) A) and B)

Question 18

In addition to a carbonyl stretch, which of the following molecules exhibits two characteristic stretches at 2700 and 2800 cm-1?

Accepted Answer

A)   (CH3CH2) 2CO
B)   CH3CH2CH2CHO
C)   CH3CH2CO2CH3
D)   CH3CH2CH2CO2H
E)   CH3CH2CH2COClF) A) and D)
G) None of the above

Question 19

Which of the following molecules would be expected to have its C=C stretching frequency at the highest wavenumber: benzene, 1,3-pentadiene, or 1-pentene?

Accepted Answer

The answer of Which of the following molecules would be...

Question 20

Which IR band is typically more intense, the C≡C stretch or the C≡N stretch? Explain briefly.

Accepted Answer

The C≡N stretch tends to be mo...

Exam 12: Infrared Spectroscopy and Mass Spectrometry

Which region of the electromagnetic spectrum, radio or visible, is characterized by waves of shorter wavelength?

Correct AnswerverifiedShow Answer

Which of the following molecules would be expected to have its C=C stretching frequency at the highest wavenumber: benzene, 1,3-pentadiene, or 1-pentene?

Correct AnswerverifiedShow Answer

What IR absorption is characteristic of the carbon-carbon triple bond stretch in alkynes?

Correct AnswerverifiedShow Answer

What IR absorption is characteristic of the C=O stretch in aldehydes?

Correct AnswerverifiedShow Answer

Absorption of what type of electromagnetic radiation results in electronic transitions?

Correct AnswerverifiedShow Answer

The presence of which element is indicated by a peak at m/z 127 and a characteristic 127-unit gap in the mass spectrum?

Correct AnswerverifiedShow Answer

Which compound would be expected to show intense IR absorption at 2820, 2710 and 1705 cm-1?

Correct AnswerverifiedShow Answer

Ethyne (HC꓿CH) does not show IR absorption in the region 2000-2500 cm-1 because:

Correct AnswerverifiedShow Answer

An infrared wavelength of 5.81μm is equivalent to a wavenumber of ________ cm-1.

Correct AnswerverifiedShow Answer

Which of the following has a C→H stretch that occurs at the highest stretching frequency?

Correct AnswerverifiedShow Answer

Which of the following fragment peaks would not be present in the mass spectrum of n-hexane?

Correct AnswerverifiedShow Answer

How could IR spectroscopy be used to distinguish between the following pair of compounds? CH3COCH-CHCH2CH3 and CH3COCH2CH2CH-CH2

Correct AnswerverifiedC-O absorption in co...View AnswerShow Answer

Which compound would be expected to show intense IR absorption at 1746 cm-1?

Correct AnswerverifiedShow Answer

Which compound has a single, weak IR absorption at 3300 cm-1?

Correct AnswerverifiedShow Answer

The region of the IR spectrum which contains the most complex vibrations (600-1400 cm-1) is called the ________ region of the spectrum.

Correct AnswerverifiedShow Answer

In addition to a carbonyl stretch, which of the following molecules exhibits two characteristic stretches at 2700 and 2800 cm-1?

Correct AnswerverifiedShow Answer

Which region of the electromagnetic spectrum, IR or X-ray, is characterized by waves of lower frequency?

Correct AnswerverifiedShow Answer

Which compound lacks a strong, characteristic IR absorption near 1700 cm-1?

Correct AnswerverifiedShow Answer

Which IR band is typically more intense, the C≡C stretch or the C≡N stretch? Explain briefly.

Correct AnswerverifiedThe C≡N stretch tends to be mo...View AnswerShow Answer

Which has the higher speed in a vacuum, ultraviolet or infrared light?

Correct AnswerverifiedThey have ...View AnswerShow Answer

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Which compound would be expected to show intense IR absorption at 2820, 2710 and 1705 cm^-1?

Correct Answer
verified

Ethyne (HC꓿CH) does not show IR absorption in the region 2000-2500 cm^-1 because:

Correct Answer
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An infrared wavelength of 5.81μm is equivalent to a wavenumber of ________ cm^-1.

Correct Answer
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How could IR spectroscopy be used to distinguish between the following pair of compounds? CH₃COCH-CHCH₂CH₃ and CH₃COCH₂CH₂CH-CH₂

Correct Answer
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C-O absorption in co...
View Answer

Which compound would be expected to show intense IR absorption at 1746 cm^-1?

Correct Answer
verified

Which compound has a single, weak IR absorption at 3300 cm^-1?

Correct Answer
verified

The region of the IR spectrum which contains the most complex vibrations (600-1400 cm^-1) is called the ________ region of the spectrum.

Correct Answer
verified

In addition to a carbonyl stretch, which of the following molecules exhibits two characteristic stretches at 2700 and 2800 cm^-1?

Correct Answer
verified

Correct Answer
verified

Which compound lacks a strong, characteristic IR absorption near 1700 cm^-1?

Correct Answer
verified

Correct Answer
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The C≡N stretch tends to be mo...
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Correct Answer
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They have ...
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